The Cell Flashcards
Where are all organisms on Earth descended from?
They descended from a common prokaryotic ancestral cell about 3.5 billion years ago.
Theory of Endosymbiosis
About 1.5 billion years ago. Eukaryotic cells emerged when mitochondria and chloroplasts, once free-living prokaryotes, took up permanent residence inside larger cells.
Eukaryotic Cell
Complex cell with nucleus and internal membranes that compartmentalize the cell. They led to the evolution of multi-celled organisms. They make up every other form of life.
Cell Size
10-100 micrometers; human red blood cells are about 8 micrometers
Cell Theory: Schleiden and Schwann
All living things are composed of cells; Cells are the basic unit of all organisms; All cells arise from preexisting cells
Cells in General
Cells are enclosed by a membrane that regulates the passage of material between the cell and tis surrounding. They also contain nucleic acid which directs the cell’s activities and controls inheritance.
Prokayotic Cells
Have no nucleus or other internal organs.
Eukaryotic Cell
Complex cell with nucleus and internal membranes that compartmentalize the cell. They led to the evolution of multi-celled organisms. DNA wrapped with histone proteins into chromosomes, ribosomes are larger, metabolism is aerobic, cytoskeleton present, mainly multicellular with differentiation and cells are larger.
Prokayotic Cells
Have no nucleus or other internal organs. Circular, naked DNA. Ribosomes are small, metabolism in anaerobic/aerobic, cytoskeleton is absent, mainly unicellular and cells are very small.
Prokayotic Cells
Have no nucleus or other internal organs. Circular, naked DNA. Ribosomes are small, metabolism in anaerobic/aerobic, cytoskeleton is absent, mainly unicellular and cells are very small.
Microscopes
Main tool for studying cells. They magnify an image over 100,000 times. Resolution, high magnification and high resolution are characteristics of a good microscope.
Microscrope: Resolution
clarity of the image
Microscopes and People to Know
Antoine van Leeuwenhoek developed the first microscope and Robert Hooke advanced it which enabled him to study and name cells in a cork.
Microscopes and People to Know
Antoine van Leeuwenhoek developed the first microscope and Robert Hooke advanced it which enabled him to study and name cells in a cork.
Light Microscopes
Microscopes that use light passing through a living/dead specimen to form an image. Cells/tissue can be staines to make organelles easier to see however stains may kill cells.
Electron Microscopes
Microscopes that use electrons passing through a specimen to form an image. They have superior revolve and magnification power. However, they cannot be used to view live specimens because the specimen preparation kills the cells.
Transmission Electron Microscopes
Used to study the interiors of cells. The images appear flat and 2D. The tissues must be cut into very small pieces and exposed to a fixative that stops all biochemical activity. The tissue is then dehydrated, embedded in a polymer, cured overnight and sliced on an ultramicrotome.
Scanning Electron Microscopes
Used to study the surface of cells. The images appear 3D. Specimens are coated with a heavy metal such as gold and are placed directly on the microscopes for observing. Specimens are not alive.
Phase-Contrast Microscopes
Used to examine unstained, living cells. It is often used to examine cells growing in tissue culture.
Phase-Contrast Microscopes
Used to examine unstained, living cells. It is often used to examine cells growing in tissue culture.
Cell Fractionation
Using an ultracentrifuge to spin liquids at high speeds and separate them based on differences in density. Tissues/cells are first mashed up in a blender to form a homogenate. The most dense particles such as nuclei are pushed to the bottom, followed by mitochondria and ribosomes. The supernatant, liquid above the pellet, can be poured off an re-spun.
Cell Fractionation
Using an ultracentrifuge to spin liquids at high speeds and separate them based on differences in density. Tissues/cells are first mashed up in a blender to form a homogenate. The most dense particles such as nuclei are pushed to the bottom, followed by mitochondria and ribosomes. The supernatant, liquid above the pellet, can be poured off an re-spun.
Freeze Fracture and Freeze-Etching
Multistep techniques used to prepare a detailed cast of the membrane. The tissue is then digested away leaving only the cast which can be examined under the electron microscope.
Tissue Culture
Used to study the properties of specific cells in vitro. Cell lines can be grown in culture for years and while the cells are growing they can be studied with a phase-contrast microscope.